I have been doing a dating of a sediment core for a customer: A consultant company dealing with environmental consequences due to mining activities. The company took sediment cores in a lake close to the mines and I did a dating, chronology, using the isotopes Pb-210 and Cs-137. The customer was not altogether happy with the data but I had to prove to them that the sampling techniques they used probably disturbed the upper part of the core. They did the sampling themselves and when I asked about how they took the sediment core it became evident that the technique of dropping a sediment sampler down into the soft sediment has a great risk of disturbing the core. There are plenty of evidence among environmental scientists working on sediments that the sampling itself is a critical part. The chain is not stronger than the weakest link. The rest of today has been devoted to discussions of an application that we aim to send to the natural science council. It concerns methods to use radioisotopes produced in the atmosphere from cosmic radiation (cosmogenic radioisotopes) as tracers for cloud formation. It will work, scientifically. But do we like to undertake this huge project if we are granted the money? We are doing 1000 of small scientific projects. Can we take on more? What of our old projects should we then stop? Since we are several people from various groups it is not easy to agree on every point. During the meeting I found myself spending most of the time thinking of a technique to improve the analysis of the rare U-isotope U-236. I can see from the meeting notes here in front of me that I will probably not try to get involved in the cosmogenic project. Too much work for a limited point of interest. Time is now 17 and I will spend 2h in the lab preparing for tomorrow analysis of a Baltic Sea sediment core I received in 2010. I will analyse only the top 10cm to determine the mixing (movement) of sediments caused by currents and possibly gas bubbles. The sediments are anoxic, black from FeS and have no signs of benthic life. I need to use the short lived Th-tracers Th-228 and Ra-228 to determine this sediment mixing. Analytically I will digest the sediment samples in acids following ashing. I will then use a combination of ion exchange and classical inorganic chemistry to isolate Th and then measure its radiation which is by emission of alpha particles (alpha spectrometry). From the gradient of Th-228/Ra-228 I can calculate the sediment mixing and by assuming this mixing to be more or less constant for all years past I can correct the sediment accumulation rate I have determined previously by Pb-210 and Pu-isotopes. I will then use this corrected sediment accumulation rate together with my data on uranium isotopes and stable rhenium to calculate the rate at which these two redox sensitive elements are removed from Baltic Sea water at present. I would then like to operate on samples from the longer cores from the Gotland Deep to see what the data there can tell me but that’s another story. Interesting too!